Luminescence

Spontaneous emission of light by a substance

Luminescence can be simply defined as any emission of visible electromagnetic radiation (light) not ascribable directly to incandescence. Incandescence emerges at high temperatures due to thermal radiation; in contrast, because luminescence is often independent of temperature, it is sometimes termed cold light. However, some kinds of luminescence (e.g., candoluminescence, pyroluminescence, thermoluminescence) are associated with or require elevated temperatures.

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